Is sandstone clastic or non clastic?

So, Sandstone: Clastic or Non-Clastic? Let’s Clear That Up.

Okay, let’s get straight to the point: sandstone is 100% a clastic sedimentary rock. End of story? Not quite! That simple label actually tells a pretty cool story about how this common rock comes to be. Basically, it’s all about bits and pieces of older rocks getting glued together. To really get it, we need to peek into the world of sedimentary rocks and how they’re made.

Clastic vs. Non-Clastic: The Great Sedimentary Divide

Think of sedimentary rocks as falling into two main camps: clastic and non-clastic. It’s a bit like sorting LEGOs – you’ve got the pre-made bricks (clastic) and the stuff you build from scratch (non-clastic).

• Clastic rocks? These are the recyclers of the rock world. They’re made from bits and bobs – the eroded and weathered leftovers of other rocks. Imagine wind and water carrying tiny rock fragments, like nature’s cleanup crew. These fragments, called clasts, eventually settle down in layers, get squished together, and cemented into solid rock.
• Non-clastic rocks? Now, these guys are a bit different. They’re either born from chemical reactions or from good old-fashioned organic matter. Chemical sedimentary rocks pop up when minerals dissolved in water decide to come out of solution – like when seawater evaporates and leaves behind salt. And biological sedimentary rocks? Think coal, formed from ancient plant gunk, or some limestones, built from the shells and skeletons of sea creatures.

Sandstone: A Clastic Case Study

So, why is sandstone clastic? Well, it’s mostly made of sand-sized grains – we’re talking about bits between 0.0625 and 2 millimeters across. That’s about the size of, well, sand! These grains are usually tough silicate minerals like quartz (the most common) and feldspar. But you can also find tiny rock fragments mixed in – geologists call these “lithic fragments.”

Here’s the recipe for sandstone, clastic-style:

Sandstone’s Many Faces

While quartz is often the star of the show, sandstone can come in different flavors depending on what’s in it. Geologists like to classify them based on the amounts of quartz, feldspar, and those lithic fragments we mentioned:

• Quartzose sandstone: This is the pure stuff – over 90% quartz. It’s tough, resists weathering, and basically laughs in the face of erosion.
• Arkose: Got more than 25% feldspar? You’ve got arkose. This type often tells us that nearby granitic or metamorphic rocks are eroding quickly.
• Lithic sandstone: These guys have a good helping of lithic fragments. They can look kind of speckled, like salt and pepper, because of those dark rock bits.

Oh, and the color? That depends on what’s cementing everything together. Iron oxides give you those beautiful red and brown sandstones you see in the desert Southwest, while calcite often leads to a more subdued gray.

The Bottom Line

So, there you have it. Sandstone is a clastic sedimentary rock, plain and simple. It’s all about those sand-sized grains getting weathered, transported, deposited, compacted, and cemented. The mix of minerals, especially quartz, feldspar, and lithic fragments, gives each sandstone its own unique personality. Now you know!